Swath-based inkjet printing systems create a printed image by controlling an inkjet printhead to print an image swath in accordance with printhead control data. An inkjet printhead comprises an array of printhead nozzles through which drops of ink, or other fluid, may be ejected. The printhead control data is derived from an image to be printed and describes the number of ink drops to be deposited by each nozzle of each printhead at different pixel locations on a media.
To overcome problems common in swath-based printing, such as inter-swath banding, printing systems often implement multi-pass printing. In multi-pass printing each swath is generated as a result of multiple passes of a printhead across a print zone. In conjunction with multi-pass printing, print masking techniques are used to temporally distribute the total number of ink drops to be deposited at each pixel location on a media (as described in the printhead control data) over one or multiple printhead passes.
The design of print masks has an important role in defining the performance of a printing system. For example, known print masks that enable high-quality images (such as photo quality) to be printed generally require a high-number of printhead passes, and hence have a low printer throughput. Other print known print masks enable high-speed printing, use, for example, from 2 to 4 printhead passes, but consequently print quality is reduced.